Amplifier



FIG. 1 is a perspective view of an amplifier as seen from the front, top, and left side;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top end view thereof; and,

FIG. 7 is a bottom end view thereof.

The dotted line portions of the drawings represent environmental structure only and do not form part of the claimed design. 

CLAIM The ornamental design for an amplifier, substantially as shown and described. 